1. Field of the Invention
The present invention relates to a dielectric ceramic composition, showing large absolute value of capacity temperature characteristic within a wide temperature range, and an electronic device, having a dielectric layer constituted by said dielectric ceramic composition.
2. Description of the Related Art
VR (Voltage Regulator) is a system regulating voltage of DC/DC converter, which drives CPU of notebook computer or so. Inductor resistance (Rdc) detects output voltage of VR, however, there was a problem that an error arises in the detected value since Rdc varies due to heat. Therefore, it is required to use properly within a wide temperature range. In the present state, NTC thermistor is used to revise the error of the detected value.
Further, capacitor is normally used for circuit of VR system. It is thought that, by using a capacitor showing large absolute value of capacity temperature characteristic, such as around −5000 ppm, said error can be revised. NTC thermistor is not required with this method, and its cost is reduced with advantage.
On the other hand, there is a demand for a capacitor showing small absolute value of capacity temperature characteristic, therefore, a capacitor showing large absolute value of capacity temperature characteristic is scarcely informed. Note that the absolute value of capacity temperature characteristic of normal capacitor is at most around −1000 ppm/° C. or 350 ppm/° C.
Japanese Utility Model Publication No. H5-61998 describes a ceramic capacitor using ceramic as dielectric wherein said ceramic shows capacity temperature characteristic of −1500 ppm/° C. to −5000 ppm/° C. and includes 20 to 95 wt % of SrTiO3. However, dielectric layer composition of ceramic capacitor described in Japanese Utility Model Publication No. H5-61998 is partially unidentified and the other components are totally unidentified. Further, said publication does not indicate temperature range wherein said capacitor temperature characteristic is shown.